Well bore packer and actuating means therefor



Feb. 8, 1955 M. a. RIORDAN, JR., ETAL 2,701,615

WELL BORE PACKER AND ACTUATING MEANS THEREFOR 6 Sheets-Sheet 1 Filed March 16, 1951 MHTTHEW E. 2/0909 Je. MQEEV 5. ame? #445 5. HflMBLV INVENTORS M. B. RIQRDAN, JR. ETAL 0 WELL BORE PACKER AND ACTUATING MEANS THEREFOR I Feb. 8, 1955 6 Sheets-Sheet 2 Filed March 16, 1951 INVENTORS By F36 prraeva s Feb. 8, 1955 M. B. RIORDAN, JR., EI'AL WELL BORE PACKER AND ACTUATING MEANS THEREFOR Filed March 16. 1951 N WWW WW WW Q WJW- 6 Sheets-Sheet 4 IOG BY 6M6 Feb. 8, 1955 M. B. RIORDAN, JR, ETAL- 2,701,615

WELL BORE PACKER AND ACTUATING MEANS THEREFOR Feb. 8, 1955 M. B. RIORDAN, JR., EI'AL 2,701,615

WELL BORE HACKER AND ACTUATING MEANS THEREFOR Filed March l6. 1951 6 Sheets-$heet 6 INVENTORS H s-.15. I BY i,

United States Patent WELL BORE PACKER AND ACTUATING MEANS THEREFOR Matthew B. Riordan, Jr., La Habra, Harry B. Boller, Alhambra, and Allen E. Hambly, South Gate, Califi, assignors to Byron Jackson C0., Vernon, Calif., a corporation of Delaware Application March 16, 1951, Serial No. 216,038

16 Claims. (Cl. 166--63) This invention relates generally to well packers, and particularly to a novel expansible packer especially designed for use as a by-pass packer in conjunction with a flow meter or other instrumentality necessitating the diversion of fluid flow from a large diameter flow passage into a relatively small diameter flow passage.

Valuable information as to the production characteristics of an oil, gas or water well could be obtained if it were possible to make accurate flow measurements at various levels in the well while it is producing. Thus the relative contributions from various zones of a producing formation to the total production from the formation could be determined. However, inasmuch as oil and gas wells are commonly produced through well tubing, it is apparent that in order to obtain flow measurements while the well is producing, the flow measuring instrument must be introduced into the well either through the well tubing or through the annulus between the tubing and the casing. The tubing is usually of an outside diameter on the order of 2 to 3", and hence an instrument insertible through the tubing must have an outside diameter not exceeding 1%.. 0n the other hand, the well casing in which the flow measurements are to be taken is most commonly 7" in diameter. It is obvious that with a 1 /2 instrument in a 7" flow passage, it is impossible to obtain accurate measurements of low flow rates or of small changes in flow rate.

This problem can be solved by providing means bridging the annular space between the relatively small flow measuring instrument and the well casing and capable of diverting all or substantially all of the fluid flow through the instrument. A general object of this invention is to provide such means.

Another object of the invention is to provide such means in the form of an expansible and collapsible bypass packer capable of being contracted to a diameter which will permit its being passed through the usual well tubing, and capable of being expanded to a diameter at least equal to the inner diameter of usual well casing.

In making flow measurements in a well the instrument is moved to diiferent levels to obtain readings of flow rates from or into various zones. Accordingly a bypass packer associated with the instrument must be capable of being moved upwardly or downwardly while in expanded condition. The well casing frequently varies in diameter at different elevations, it often has inward projections such as burrs around gun perforator holes, and is frequently encrusted with rust, paraflin or sludge. Hence the packer must be capable of accommodating itself to such anomalies while being moved through the well. It is still another object of this invention to provide a packer of the above character which possesses sufficient inherent flexibility, when expanded, to permit it to pass readily through sections of casing of sub-normal diameter, and to permit it to pass over inward projections on the wall of the casing, all while maintaining a substantially complete and effective sealing off between the associated instrument and the wall of the casing.

It is still a further object of the invention to provide, in combination with a packer having the foregoing characteristics, means controllable from the surface of the well for expanding the packer after it has passed through the small diameter tubing and into the relatively large diameter flow passage defined by the well casing.

Yet another object of the invention is to provide packer expanding means actuated by means controlled electrically from the surface of the well, thereby rendering it ice possible to employ the packer in conjunction with an instrument suspended from a conductor cable.

A still further object of the invention is to provide means whereby a packer of the foregoing type may be collapsed after being expanded in the well, to permit its retraction from the well through small diameter tubing.

A still further object of the invention is to provide a novel packer of all-metal construction, thus avoiding the use of rubber-like material or fabric and their inherent susceptibility to high well temperatures, abrasion, and deterioration when exposed to certain well fluids.

Other objects and advantages of the present invention will be apparent from the following detailed description of a presently preferred embodiment of the invention, reference being had to the accompanying drawings wherein:

Figures 1 and 2 are perspective views of a crowned spring metal strip forming an element of the packer element of the present invention;

Figure 3 is a view in side elevation of the packer element in collapsed condition;

Figure 4 is a fragmentary perspective view on an enlarged scale, taken substantially on line 4-4 of Fig ure 3, showing the overlapping arrangement of the crowned metal strips;

Figure 5 is a view similar to Figure 3 but showing the packer element in expanded condition;

Figure 6 is a view generally similar to Figure 5 but showing in broken lines various profiles of the packer element when moved through bores of varying diameters;

Frgure 7 is a view in side elevation of an assembly of flow meter, packer element and packer actuator in op erative position in a well;

Figure 8 is a view, partly in longitudinal section, of a typical flow meter with which the packer of the present invention is adapted to be associated;

Figures 9a and 9b are longitudinal sectional views of the upper and lower portions, respectively, of a preferred form of packer and packer actuator embodying the invention, these views being taken on the broken section line 99 of Figure 14 and illustrating the packer element in collapsed condition and the actuator mechanism cocked for actuation by remote control;

Figures 10a and 10b are views corresponding to Figures 9a and 9b but showing the packer element in expanded condition and showing the parts of the actuator mechanism in the positions they assume after expanding the packer element;

Figures lla and 11b are views corresponding to Figures 9a and 9b but showing the packer element in collapsed condition and showing the actuator mechanism in fully deenerglzed condition, this being the condition as the assembly is retrieved from the well after completing a flow survey;

Figure 12 is a view in side elevation of a special tool employed In cocking or re-setting the actuator mechamssn;

Filgzure 13 1s an end view of the tool shown in Figure Figures 14, 15, 16, 17 and 18 are transverse sectional views taken respectively on lines 1414, 1515, 1616, 17-17 and 18-18 of Figures 10a and 10b.

Referrmg to Figures 1 to 6 inclusive, an important feature of the invention is a packer element, generally designated A, of novel construction and possessing unique and distinctive characteristics. This packer element comprises essentially a circumferential series of longitudinally extending crowned spring metal strips assembled in overlapping relation so as to form a cylindrical structure when in contracted condition, as shown in Figure 3. The term crowned spring metal strip, as used in this description and in the appended claims, is intended to mean and include a strip of any metal such as steel, copper-beryllium alloy or the like, having good spring qualities and of relatively thin, transversely curved cross-section. A typical example of this material which is readily available commercially is that used in steel measuring tapes. Figure 1 illustrates a piece of such material, designated 10.

A crowned spring metal strip, when straight, is characterized by high columnar strength or resistance to bending or buckling when subjected to longitudinal compression.

This high columnar strength is attributable to the transverse curvature of the strip, and is proportional to the degree of curvature. Hence upon the application of a transverse force, such as indicated at F3 in Figure 2, at any point on the strip intermediate its ends, the result- 1ng bending of the strip is accompanied by a reduction of its transverse curvature and a corresponding reduction in the columnar strength of the strip. It requires only slight bending of the strip to transform the transversely curved section into a straight section at the point of application of maximum bending stress. This occurs abruptly w1th a snap-action, and is accompanied by a sharp reduction in bending strength at the transversely straightened section. Thus upon initially bending a strip as indicated in Flgure 2, the magnitude of the oppositely directed forces F1 and F-Z applied to the ends of the strip to further bend the strip is only a small fraction of the longitudinally applied force required to buckle the strip when straight. Because of the inherent resiliency of the strip, it tends to ztraighten out upon release of the longitudinally applied Qrce.

The aforementioned characteristics of a crowned spring metal strip are availed of to maximum advantage in the packer element A of the present invention. As shown in Figures 3 and 4, a plurality of strips are arranged longitudinally in circumferentially overlapping relation about a common axis with their concave sides facing radially inwardly, thus forming a generally cylindrical structure. As shown most clearly in Figure 9a, the strips are secured in assembled relation by clamping their adiacent ends between inner and outer rings 12 and 14. The assembly operation may be performed simply and inexpensively by arranging the strips on a suitable mandrel and pressing the end rings onto the res ective ends.

The extent of overlapping of the strips should be such th t when the intermediate porti n of each strip is bulged radially outwardly a distance sufficient to cause it to contact the well casin the stri s still maintain their overlapping relationship even. at the point of maximum diameter. as indicated in Figure 5. The required extent of overlap depends on the wid h of the individual stri s. and should be commensurate with the ratio of expanded diameter o collapsed diameter of the packer element.

When the marker element A is expanded into the osition shown in Figure 5, by mechanism to be described hereinaf er, its maximum diameter will lie in a transverse plane midway between the ends of the packer element if the unrestricted maximum diameter does not exceed the diameter f the bore in which the packer element is posi tioned. However. because of the low bending stren th of the strips at the bent region, the lane of maximum diameter may be shifted in either direction b the ap lic ion of a relatively small axial force at the bent re i n. This movement of the plane of maximum diameter results in a reduction in maximum di meter, such reduction being proportioned to the extent of displacement from the median transverse plane. This characteristic is important in connection wi h he intended primary use of the packer element, inasmuch as it allows. the packer element toaccommod te itself t variations in the diameter of the well casi through which it is moved while in expanded condition.

Thus, as illustrated in Figure 6, the normal diameterof the well casing m be that indicated by the solid lines 16. the normal rofile of the ex anded packer element being indicated by the solid line 18. Assuming that the packer element is being moved downwardly and encounters a section of casin of sli h ly reduced-diameter. as indicated by dotted lines at 20. The upward and inward pressure exerted on the leading side of the region of maximum diameter of the maker element as it enters the section of casin of reduced di meter displaces the region of maximum diameter upwardly a distance sufficient to reduce the maximum diameter to that of the casin and causes the packer element to assume the shape indi ated by dotted lines at 22. A still smaller casing diameter, indicated by dot-and-dash lines at 24, will further deform the packer element into the profile indicated at 26. Similarly, if the packer element should be moved upwardly in the well and should encounter a section ofcasing of a diameter indicated at or 24, its region of maximum diameter will be moved downwardly to produce; packer profiles as indicated respectively at 22a and 26a.

As p int d uther in ft r, a p eferre ype of packeractuator applies a predetermined compressive force, as by means of a spring, to the ends of the packer element, the magnitude of this force being such as to tend to expand the packer element to a diameter somewhat in excess of the maximum diameter of the Well casing in which it is designed to be operated. In this manner the packer element exerts moderate pressure against the wall of the casing, sufiicient to effect a substantial seal but insufficient to offer any substantial resistance to movement of the packer element upwardly or downwardly in the well casing.

It will be observed that the bend in the median portion of each of the metal strips 10 has a substantial radius of curvature, thereby presenting a nicely rounded outer surface for sliding contact with the well casing. This streamlined contour contributes materially to the ease of selfadjustment of the packer element to compensate for variations in casing diameter and to permit it to pass over projections on the casing wall without damage to the packer element.

It should be understood that the intended function and purpose of a packer element constructed as described herein is merely to divert the flow of fluid in the well casing into the relatively small diameter central passage defined by the confined ends of the strips 10, and thence through a correspondingly small diameter flowmeter, so that substantially all of the fluid passes through the flowmeter. Under these circumstances the only pressure differential prevailing across the packer element is that resulting from the pressure drop caused by friction losses in the small diameter passages through the packer element and the fiowmeter. It is not intended that the packer element should be capable of withstanding any substantial pressure differential. In fact, the aforementioned characteristic of low resistance to axial displacement of its region of maximum diameter upon application thereto of a relatively small axial force renders it inherently incapable of establishing or maintaining a substantial pressure differential. Furthermore, although the metal-to-metal contact betwen the overlapping faces of the strips 10 is adequate to eifect a substantial seal against leakage of fluid between these faces, it will be obvious that such leakage would occur if it were attempted to establish a substantial pressure differential across the packer element.

With respect to leakage of fluid between the strips 10, it has been ascertained in actual practice that in the case of liquids such as oil or water and with rates of fiow other than extremely low rates, this leakage is of such minor nature as not to materially affect the accuracy of the flow measurements. However, when measuring extremely low rates of flow of liquids or when measuring gas flow rates it has been found desirable to augment the sealing effect of the metal-to-metal contact between the faces of the strips 10 by coating such faces with a suitable plastic sealing compound. In order to be effective for this purpose the sealing compound should have the property of good adhesion to the metal strips and should be.

of such viscosity as to cause it to yield or flow as the extent of overlapping of the strips ltlchanges during expansion and contraction of the packer element. It should also be chemically and physically stable at all well tem-' peratures commonlyv encountered, and it should be insoluble in hydrocarbons. We have found that a wellknown valve lubricant marketed under the name Nord-- coseal No. 54-5 is typical of various. compounds. which meet these specifications. In. applying the sealingcompound, it should be inserted by' any suitable means between the overlapping faces of thestrips 10. while the packer element is in collapsed condition, to deposit a film of the compound between those faces.

Referring: now to Figures 7, 8, 9a and 9b, the packer:

element A is shown assembled with a flowmeter unit B and a packer actuator assembly C, the entire assembly being shown in Figure 7 as being suspended from-a conductor cable 30 in the well casing 16 with the packer element A expanded after the assembly has been lowered.

through the string of production tubing 32. As. shown connected at its lower end to the upper housing-sectionv 38 of the actuator assembly C. Animpeller shaft-40 is journaled in the housing 34 and'has anI impeller 42 afii-xed theret0. A series of stationary deflector vanes: 44 is mounted in the housing, below the. impeller, these. vanes being inclined oppositely to the inclination oftheavanesr of the impeller 42 so as to deflect the upwardly flowing fluid against the impeller vanes. Below the stationary vanes 44 the interior of the housing'34 communicates with the interior of the actuator housing section 38, which serves as a fluid by-pass conduit through the packer element A. Fluid outlet ports 46 are formed in the wall of the housing 34 above the impeller 42, through which the fluid is discharged into the well casing after acting on the impeller.

The flowmeter B is of the type in which rotation of the impeller and its shaft produces interruptions in an electrical circuit,-the frequency of the interruptions being proportional to the speed of rotation of the impeller shaft and therefore constituting a measure of the rate of flow of the fluid through the instrument. As shown, the impeller shaft 40 is provided with a short commutator section 48 consisting of alternating conducting and nonconducting surfaces. A brush 50 engages the commutator section and is connected by a conductor 52 through a resistor 54 to a ground connection 56 on the housing 34. A second brush 58 contacts an uninterrupted portion of the surface of the shaft 40 and is connected through a conductor 60 to the conductor core of the cable 30. One of the strands of the outer steel armor of the cable 30 is grounded to the housing 34 at 62, thus completing an electrical circuit from a voltage source at the ground sur' face, such as a battery or generator (not shown), through the insulated conductor core of the cable 30, conductor 60, brush 58, shaft 40, brush 50, conductor 52, resistor 54, housing 34, the steel armor of the cable 30, to the ground side of the voltage source at the surface. Upon impressing a voltage on this circuit, rotation of the impeller shaft 40 by the fluid flowing past the impeller causes the commutator 48 to alternately open and close the circuit, thus producing a variable frequency signal at the surface which may be translated into rate of flow of the fluid. With this arrangement it is obvious that the shaft 40 must be insulated from the housing 34, suitable insulation being provided as indicated at the shaft bearings and at other necessary points.

As described in detail hereinafter, the operation of the packer actuator assembly C to expand the packer element A is initiated electrically, upon initial closing of the abovedescribed electrical circuit by manipulation of a switch (not shown) at the surface. The electrical impulse for initiating operation of the actuator assembly C may be transmitted thereto by a branch circuit including the insulated shaft 40. As shown at the lower extremity of Figure 8 and at the upper extremity of Figure 9a, a plugand-socket connector 64 provides a detachable electrical connection between the shaft 40 and a conductor 66 which extends downwardly through the actuator assembly as described hereinafter.

Referring now to the packer actuator assembly C, it has been stated previously that each individual strip of the packer element A possesses an appreciable columnar strength when straight, but when initially bent by application of a transverse force at any point along its length, the resultant straightening of the transverse section at the point of bending produces a sharp decrease in bending strength at that point. Thereafter the strip may be bent further by moving the ends thereof toward each other by application of a force very materially less than the longitudinally applied force required to buckle the strip when straight. When a plurality of such strips are assembled as shown in Figure 3 and described hereinabove, each strip is reinforced against buckling by several adjacent overlapping strips thereby producing a structure having a columnar strength, when in the collapsed condition shown in Figure 3, which is appreciably greater than the aggregate of the columnar strengths of the individual strips. However, upon application of a radially outward force to certain of the strips at points in a transverse plane intermediate the ends of the packer element, and upon the subsequent slight outward bulging of the structure in the region of such plane, the columnar strength of the structure is reduced sharply.

This characteristic of the assembly of strips is fully availed of in the actuator assembly described herein by pre-loading the packer element, in its collapsed or running-in condition, with an axialcompressive force which is of insufl'icient magnitude to buckle the column when it is straight, but which is of sufficient magnitude to continue the buckling andconsequent expansion of thepacker element once it has been initially buckled byapplication of a radially outwardly applied force. To ex pand the packer element, it therefore becomes necessary only to apply the radially outward force by means controllable from the well surface, and thereafter the axial compressive force automatically becomes effective to complete the expansion and to maintain the packer element expanded.

Generally speaking, both the axial compressive force and the radially outwardly directed force are preferably supplied by springs in which the required energy is stored by initial cocking of the actuator mechanism prior to running the device into a well. The release of the energy stored in the spring which furnishes the axial compressive force is initially prevented by the columnar strength of the collapsed packer element against which one end of the spring acts, part of this energy being released upon expansion of the packer element. The remaining energy stored in this spring to maintain the packer in its expanded condition may subsequently be released, to per mit the packer element to return to its collapsed condition by its inherent resiliency, by releasing a latch which releasably retains in fixed position an abutment engaging the other end of the spring. The energy stored in the spring which supplies the radially outwardly directed force is released by the release of latch mechanism associated with an abutment engaging one end of the spring, the latch mechanism being releasable upon actuation of electrically controlled means under the control of the operator at the ground surface. This spring is normally completely de-energized during its operating cycle, so that upon'de-energization of the first-mentioned spring and consequent self-collapsing of the packer element, the device may be withdrawn from the well through the tubing 32 with all initially stored energy released.

A specific embodiment of an actuator mechanism incorporating the above-mentioned principles of operation will now be described, reference being had first to Figures 9a and 9b, the latter figure being a downward extension of the former. In these figures the packer element A is collapsed and the acuator mechanism is shown in .cocked corllldition in readiness for lowering the assembly into a we The actuator mechanism is enclosed within a threesection housing comprising the upper section 38, an in termediate section 70 and a lower section 72, threadedly interconnected to each other and the upper section 38 being adapted for threaded connection to the flowmeter housing 34. The packer element A is mounted on the upper housing section 38, with its upper extremity abutting a downwardly facing external shoulder 74 formed on the housing section. The lower extremity of the packer element is engaged by the upper end ring 76 of a screen 78. The housing section 38 is provided, adjacent the screen 78, with a plurality of longitudinal slots 80 which, as shown in Figure 17, are in this embodiment three in number and spaced 120 apart. Retaining screws 82 extend from the screen end ring 76 through the respective slots 80 and are threaded into the upper headed portions of three equally spaced webs formed integral with the hub of a floating spider 84 slidably mounted within the housing section 38 and guided by the inner wall .thereof. The retaining screws serve to interconnect the spider 84 and the screen end ring 76 to constrain the later to move vertically with the spider. The slots 80 also guide the screws 82 and thus restrain the spider against rotation relative to the housing.

The upper portion of the hub of the spider 84 is internally threaded to receive the lowermost coils of an extension spring 86 and thus anchor the spring to the spider. The upper extremity of the spring 86 is similarly threadedly connected to the hub of a second spider 88 guided within the housing. A guide screw 90 is threaded into the outer end of one of the three webs of the spider 88, as shown most clearly in Figure 16, and projects into a longitudinal slot 92 formedin the housing to restrain the spider against rotation relative to the housing.

A latch sleeve 94 is threadedly connected at its upper extremity to the spider 88 and extends downwardly therefrom through the floating spider 84 and into the upper portion of the intermediate housing section 70 (Figure 9b). Adjacent the lower extremity of the latch sleeve 94 a circumferential arcuate groove 96 is formed in its outer surface. A stationary spider 98 is clamped between the lower extremity of the upper housing section 38 and an internal shoulder 100 formed on the intermediate housing section-70', the hub of the spider 98: having a plurality of radial bores 102 in each of which is disposed a ball detent 104. In the cocked position of the'mechanism' as shown in Figures 9a and 9b, the groove 96 in the. latch sleeve 94 is aligned with the bores 102 and the ball 'detents 104 project partially from their bores into the groove 96 to thereby lock the sleeve 94 in-fixed relation to-the stationary spider. In this positionof the latch sleeve, the-spring .86 is extended materially beyond its free or relaxed length and hence it is energized and exerts an upward force on the floating spider 84. This upward force is transmitted by the retaining screws 82 to the screen end ring 76 and thence to the lower extremity of the packer element A, thus exerting anaxial compressive-force on the metal strips 10' of" the packer element. This force is less than that required to overcome the columnar strength of the packer element when it isfully collapsed, but it is sufficient: to fullyexpand the packer element into the condition shown in Figure 7 or Figure aonce. the strips 10 have been initially buckled.

The ball detents 104 arereleasably retained in their interlocking position shown in Figure 9b by engagement thereof with the inner wall of an enlarged recess 106 formed in the upper portion of a latch cage 108. The cage 10S is-yieldably urged upwardly to bring the shoulder 109" into abutting engagement with the lower end of the stationary spider 98 by a compression spring 110 interposed between an internal shoulder 112 in the housing section 70 and :a plurality of bosses 114 formed on the cage. It will be observed that the upper portion ofthe recess 106 is counterbored at 116 to a larger diameter, whereby upon slight downward movement of the cage 108 against the force of the spring 110, the ball detents may move. radially outwardly into the counterbore 116 and out of the groove 96, thus releasing the latch sleeve from the stationary spider. The arrange- 1116111: whereby this downward movement of the latch cage 108 is effected will be described hereinafter.

Referring again to Figure 9a, a compression spring 118' isinterposed between the spider 88 and a third movable spider 120. To the upper surface of the hub of the spider 120 there are pivotally secured, as by pivot pins 121, three expander arms 122a,, to the upper extremity of each of which there is pivotally connected by a pivot pin 123' an identical but inverted expander arm 12212. The upper extremities of the arms 12212. are pivotally connected by pivot pins 125 to the hub of a stationary spider 124 which is secured by set screws 126- to the housing (Figure 14). The arms 122a and122b are disposed in radial. planes and, as shown in Figure 15, the axes of the pivot pins 121, 123 and 125 all extend perpendicular to the planes of the respective arms so that the arms may move radially outwardly and inwardly. The housing section 38 is provided with three longitudinal slots 128 each aligned with a respective. pair of arms 122a, 122k and, of such width as to permit the arms to move outwardly through their respective slots and into engagement with the packer element A. It. will be observed that the. pivotal connections 123 between the. adjacent ends of the two sets. of. arms are disposed radially outwardly with: respect to the location of the pivot pins 121 and 125, whereby upon upward movement of the. spider 12 the arms will be pivoted outwardly. A short distance above. the spider 120 in its position as shown in Figure 9a, there are provided three inward projections 130 formed on the inner wall of the housing, each. projection being disposed in axial alignment with a. respective. web of the spider 120 and serving as abutments limiting the. upward movement of the spider and hence limiting the outward pivotal movement of the arms 122a and 12%.

It has been previously stated that in the cocked condition of the actuator mechanism as shown in Figures 9a and 9b the spider 88- is latched in fixed position. With the spiders 88 and 120 in the relative positions shown in these figures, the spring 118 interposed therebetween is under compression and hence tends to move the spider 120 upwardly and thusv pivot the arms 122a, 122b outwardly. However, in this running-in. condition-the spider 120 is also releasably latched in fixed position. A trigger sleeve 132 is secured at its upper extremity to the spider 1'20 and extends downwardly therefrom within the latch sleeve 94 and concentric therewith. As seen in Figure- 9b, the trigger sleeve proof the. actuator head 150.

8 jects downwardly below the lower extremity of' the latch sleeve and has secured 'to its lower extremity a latch head-134 having axially spacedupper and lower circumferential grooves 136 and 138 in its'outer surface.

A plurality of radial bores 140' extend through the latch cage 10% adjacent its lower extremity, there being a ball detent 142 in each bore. In the'cocked'condition of the mechanism the upper groove 136 in'the latch head 134 is aligned with the. bores 140 and the detents- 142 are disposed-partly in the groove 136 and partly in the bores to releasably' latch the trigger sleeve 132 to the cage 108. The sleeve tends-to move upwardly under the influence of the spring 118', but upward movement of cage 108 is prevented-by the abutment of its shoulder 109 against the stationary spider 98; Thus so long as the-d etents 142 engage the groove-136" the spider and the pivoted spreader arms 122a and 122b are held, in their retracted or cocked positions.

Disposed below the latch cage 108 is a trigger cage.

144 having an enlarged central recess. 146' in itsv upper portion into which the lower end of.the latch cage ex.- tends, the bore of the upper portio'n'oi the recess having only a working clearance, with the detents. 142 so. as to retain them firmly and securely in the groove136. An internal arcuate groove 148is formed in the wall of the recess 146 slightly below the median transverse. plane of the recess. In the cocked condition the, groove.- 148 is ofiset downwardly from the plane of the detent. bores The trigger cage rests on an actuator head 150, being yi'eldingly urge'di downwardly thereagainstby a compression spring 152. interposed between the upper end surface of the trigger cage and the bosses 114 formed on the latch cage 108.v The trigger cage. is adapted to be moved upwardly a short distance, by electrically controlled means to be described presently, to bring the groove 148, into alignment with, the detent bores 140 and thus permit the detents to be cammed out of the groove 136. When this occurs, the trigger. sleeve 132. and its associated spider, 120 are free. to move upwardly under the influence of. the spring 1118 and thus expand the arms 122a, 122b.

The lower housing section72 (Figure 9b) is of heavywalled construction and, in conjunction with a thickwalled cylinder head 154', defines, a blast chamber 156..

A plunger rod 158. is secured to the actuator head and extends downwardly through acentral opening in the cylinder head. The opening is pressure-sealed. by suitable'packing 162 which is adapted to be tightly compressed by a. follower 1.64 threaded into the open.- ing 160. The plunger rod 158v is provided with a head. 166 on, its lower end, to which is attached a small electric blasting cap 168 containing'a charge of explosive. inwhich is embedded a wire filament 170 by which the explosive is ignited upon passing an electric current through the filament. the blast drivesthe plunger rod 158 and its associatedactuator head 150 upwardly.

As previously mentioned, the conductor 66 is elec trically connected to the insulated impeller shaft. 40 of the flowmeter (Figure 8) and extends downwardly along the axis of the actuator housing sections 38 and 70-, through a central passage in the trigger sleeve 132, and. terminating within, a socket 172 disposed between the lower end of the trigger sleeve and the domed head. 174

The conductor 66 is enclosed within athin metal sleeve 176 and. is insulated. therefrom by insulation 178.

The conductor 66 and. its protective sleeve 176 re.-

main stationary during actuation. of. the various parts of. the mechanlsm, and therefore a sliding clearance is providedbetween the sleeve 176 and the bore in the trigger sleeve. 132. Also, inasmuch as the socket 172 moves vertically with the plunger rod 158 and the actuator head 150-, a sliding electrical contact is provided between the lower end of the conductor 66 and the current-conducting elements of the socket 172. As shown, the conductor projects snuglythrough a split spring ring'180 of conducting material seated in a groove in the upper portion of the socket and in contact with a conductor sleeve 182 resting on a conductor bushing 184 having. a spherical.

meter impeller shaft 40 through the conductor 66, con- Upon ignition of the explosive,.

ductor elements 180, 182 and 184 of the socket 172, actuator head 150, plunger rod 158 and conductor 186 to the filament 170 and thence to ground through conductor 188. The housing sections 72, 70 and 38, being tightly screw-threaded together and to the flowmeter housing 34, constitute a ground connection.

With the parts in the positions shown in Figures 9a and 9b, the assembly of Figures 8, 9a and 9b is cocked and ready for lowering into a well on a conductor cable. With the packer element collapsed, the maximum diameter of the entire assembly is less than the inner diameter of commonly used production tubing and hence the assembly may be lowered through the tubing. It is usually desirable to obtain a flow measurement immediately below the lower end of the tubing, and hence when the assembly reaches this point its descent is stopped and the operator closes a switch at the control station to close the circuit including the blasting cap 168 and also the flowmeter signalling circuit.

Upon firing of the blasting cap 168 the plunger rod 158 and its associated actuator head 150 are driven upwardly a short distance, which causes the trigger cage 144 to move upwardly. This results in the internal groove 148 in the trigger cage becoming aligned with the detent bores 140 in the lower portion of the latch cage 108, thus permitting the detents 142 to move outwardly partially into the groove 148 and out of the groove 136 in the latch head 134 attached to the trigger sleeve 132. The latter is thereby free to move upwardly into the position shown in Figures 10a and 10b under the influence of the compressed spring 118, causing the spider 120 to move upwardly and move the expander arms 122a, 1221; outwardly against the inner wall of the packer element A. The resulting outward buckling of the strips 10 of the packer element reduces the aggregate columnar strength of the packer element to such an extent that the upward force exerted by the extension spring 86 against the lower end of the packer element, through the spider 84, screws 82 and screen end ring 76, becomes effective to move the lower end of the packer element upwardly and thus expand the median portion thereof outwardly into sealing engagement with the well casing 16, as shown in Figure 10a. Upward movement of the trigger sleeve 132 and of the spider 120, and the consequent outward pivotal movement of the spreader arms 122a, 1221;, are limited by engagement of the webs of the spider 120 with the projections 130 on the inner wall of the housing.

After firing the blasting cap 168 the pressure developed in the blast chamber 156 holds the plunger rod 158 and the actuator head 150 in raised position until the gaseous products of the explosion have cooled and contracted sufiiciently to reduce the pressure in the blast chamber to less than that of the well fluid in the immediate vicinity of the device, whereupon the plunger rod is returned to its initial position by the higher external pressures. It will be understood that the entire interior of the actuator housing sections 38 and 70 become filled with well fluid at the prevailing submergence'pressure, only the blast chamber 156 being sealed off from the well pressure. Upon downward movement of the actuator head 150, the socket 172 is urged downwardly by a compression spring 190 interposed between the socket and the lower end of the trigger sleeve 132.

During the abovementioned upward movement of the trigger sleeve 132 the detents 142 are maintained in their outer positions, partially within the groove 148, by the cylindrical portion of the latch head 134 between the upper and lower external grooves 136 and 138. Hence during this portion of the cycle the latch cage 108 and the trigger cage 144 are interlocked and the latter is temporarily held in slightly raised position. Upon completion of the upward stroke of the trigger sleeve, however, the lower groove 138 in the latch head 134 is brought into alignment with the detent bores 140 whereupon, assuming that the plunger rod 158 and actuator head 150 have returned to their initial positions, the detents 142 are free to move into the groove 138 and are cammed out of the groove 148 in the trigger cage 144 by the downward force exerted on the cage by the spring 152. Thereupon the trigger cage is released from the latch cage 108 and moves downwardly into the positionshown in Figure 10b, in which position the wall of the recess 146 locks the detents partially within the groove 148 to interlock the trigger sleeve 132 and the latch cage 108. As describedhereinafter, this interlocking of the trigger sleeve and the latch cage against.

downward movement of the trigger sleeve relative to the latch cage is an essential step in conditioning the mechanism for subsequent collapsing of the packer element.

Attention is directed to the fact that during the abovedescribed actuation of the mechanism to expand the packer element, the position of the latch cage 108 has not changed and hence the latch sleeve 94 and its associated spider 88 remain locked in fixed relation to the stationary spider 98 by the detents 94. The extension spring 86 is therefore still partially energized and exerts suflicient upward force on the packer element to maintain it expanded against the wall of the well casing.

With the parts in the position shown in Figures 10a and 10b, the assembly is conditioned for making a flow survey in the well by moving the assembly through the interval to be surveyed and making flow rate measurements either continuously or at selected stations. As shown in Figures 9a, 10a and 17, the actuator housing section 38 is provided with three fluid inlet openings 192 in the region of the guide slots 80 but angularly oflset from these slots so as not to be obstructed by the webs of the floating spider 84. While the packer element A is in collapsed condition it extends downwardly below these inlet ports, but upon expansion of the packer element its lower extremity moves upwardly a distance sufficient to uncover these ports. The screen 78 simultaneously moves upwardly to surround the inlet ports and thus exclude any solid matter in the well fluid of a size such that, if allowed to enter the instrument, it might clog the passages or foul the flowmeter impeller 40. The fluid flowing upwardly in the well thus enters the housing through the inlet ports 192, flows upwardly in the housing to the flowmeter housing 34, past the stationary vanes 44, impinging on the impeller to rotate it, and emerges from the housing 34 through the outlet ports 46. It will be noted from the transverse sectional views, Figures 14, 15, 16 and 17, that all elements extending transversely across the path of flow of fluid through the housing, such as the webs of the spiders 84, 88, and 124, and the expander arms 122a, 122b, are of small cross-sectional area and hence do not materially reduce the flow passage area. Furthermore, these elements are all disposed in axial alignment with each other, whereby the three segmental flow passages are continuous and uninterrupted from the inlet ports 192 to the stationary vanes 44.

It should also be pointed out that it is immaterial to the functioning of the packer whether the fluid flow is upwardly or downwardly. In the case of downward flow the fluid enters the ports 46 and flows downwardly and emerges from the ports 192. In that case the flowmeter may be altered slightly by substituting a difierent impeller and stationary vane subassembly wherein the relative positions of these elements are reversed.

In order to withdraw the assembly from the well through the tubing 32, it is obvious that the packer element A must first be collapsed. The inherent resiliency of the spring metal strips 10 of the packer element causes them to constantly tend to return to a straight condition, and hence this will occur upon release of the upward axial force exerted on the packer element by the extension spring 86. The actuator mechanism disclosed herein is constructed and arranged to deenergize the spring 86 upon application of slight downward pressure exerted against the upper set of expander arms 122b to swing them inwardly a short distance about their pivots 125. This downwardly directed pressure may be applied to the arms 12% by pulling the assembly upwardly into the tubing 32 until the lower end of the tubing engages the outwardly and downwardly flared upper portion of the packer element A. It will be observed by reference to Figure 10a that when this occurs the lower end of the tubing, indicated by broken lines at32, will engage the packer element in the region of the outer portions of the arms 122b. Thereafter continued upward movement of the assembly causes the arms to be rocked inwardly, resulting in downward movement of the spider 120 and the trigger sleeve 132.

Referring to Figure 10b, it will be noted that the ball detents 142 extend partially into the lower groove 138 of the latch head 134 and thus restrain the trigger sleeve 132 against downward movement relative to the latch cage 108. Hence the initial downward movement of the trigger case 132 caused by inward pivotal movement of v thearms 122k *rnoves the latch cage 108 downwardly, compressing the spring 110. A slight downward movement of the cage 1G8 brings thecou'nterbore 1 16 in the upperendportion of the cage into alignment with the detent bores 102 in the stationary spider 98 and thus allows the detents 104 tomove outwardly. Thereupon the downward force exerted on the latch sl'eeve 9'4 by the stressed extension spring -86 cams the detents 104 out ofthe groove 96 inthe lower'end of the latch sleeve, thus allowing the latch sleeve and its associated spider 88 to move downwardly into the position shown in Figures 11a and 111). In this position of the latch sleeve and spider the spring 85 is fully relaxed and unbiased. Meanwhile during downward movement of the latch sleeve the attendant release of the energy stored in the spring 36 has permitted the floating spider 84- and the screen '78 to move downwardly to its original position, thus releasing the packer element from the previously applied compressive force. The-inherent resiliency of the metal strips 10 thereupon causes the packer element to return to its collapsed condition as shown in Figure 11a. It will be understood that the latch sleeve 94 is released from the stationary spider 98 upon onlyslight downward movement of the trigger sleeve 132 and the latch cage 108. Hence it requires only slight inward pivotal movement of the arms 12222 to efiect de-energization of the spring 86 and the consequent self-collapsing of the'packer element. This avoids the possibility of damaging the packer element by attempting to pull it upwardly into the tubing 32 while it is in expanded condition. The movements of the various elements from the positions shown in Figures 10a and 10b to those shown in Figures lla and 11b are all influenced by relatively high spring forces and consequently they occur very rapidly, with a snap-action. There is therefore no appreciable time lag between the initial inward pivotal movement of the arms 1-22b by the tubing 32 and the collapsing of the packer element.

It will be observed by reference to Figure 10b that the trigger cage 144 rests on the actuator head 15% and hence cannot move downwardly. The initial downward movement of the latch cage 10% with the trigger sleeve 132, resulting from the temporary interlocking of these elements by the detents 142, brings the detent bores 149 in the latch cage into registry with the internal groove 148 in the wall of the recess 146 in the upper portion of the trigger cage 144. This allows the detents 142 to move outwardly partially into the groove 148 and out of the groove 138 in the latch head 134, thus releasing the trigger sleeve 13:2 and its associated spider 120 for further downward movement into the position shown in Figures lla and 11b. In this position the expander arms are fully collapsed. It will be understood that the release of the trigger sleeve 132 from the latch cage 19% occurs substantially simultaneously with the release of the latch sleeve 94 from the stationary spider. Hence the expander arms 122a, 1221; are retracted into the position shown in Figure lla during the self-collapse of the packer element.

It will be noted by reference to Figure llb that in the position of the parts after collapse of the packer element the latch cage 198 is interlocked with the trigger cage 144 by the detents 142. The two cages are held downwardly in the positions shown in Figure 11b by the detents 104, which are retained in their outer positions, partially within the counterbore 116, by the latch sleeve 94.

Upon removal of the assembly from the well it may be re-conditioned for a subsequent run by replacing the discharged blasting cap 168 and its wiring 186 and 188, and by re-setting or cocking the spring mechanism. To replace the blasting cap the housing section '72 is unscrewed frorn the section 70, thus exposing the plunger rod 158 and its head 166. It will be noted that the cylinder head 154 is threadedly connected to the intermediate housing section '70 and is seated in a counterbore 194 (Figure llb) in the wall of the blast chamber 156. A packing ring 196 is compressed to provide a pressure-tight joint upon screwing the housing section 72 onto the section '70. The cylinder head 154 is provided with a normally plugged drain port 198 communieating with the interior of the housing sections 74) and 38, the drain plug being accessible for removal upon breaking the joint between the sections 70 and 72, to permit drain.- in'g off any fluid trapped in the sections 70 and 38.

To reset or cock the actuator mechanism fromjthe. condition shown in Figures 11a and 11b to the runningin condition shown in Figures 9a and 9b, the fiowmeter housing 34 is unscrewed from the upper actuator housing section 33. Cocking is efiected by inserting a'speci'al' tool into the open upper end of the housing section 38' to engage the spider 38 and move it upwardly from the position shown in Figure lla to that shown in Figure 9a. The corresponding upward movement of the latch'sleeve 94 causes the groove 96 at the lower end of the latch sleeve to register with the detent bores 162 in the stationary spider. Thereupon the detents 164 are freeto move inwardly into the groove 96, and they arecammed into this position by the curved shoulder joining the recess lite and the counterbore 11b in the upper portion of the latch cage 108, as the latch cage moves upwardly under the influence of the spring 110. The latch sleeve 94 and its associated spider 88 become locked in fixed position by the detents 104, which are retained in the groove 96 by the wall of the recess 1%.

During this upward movement of the latch cage 108 the trigger cage 1 14 is also constrained to move upwardly by reason of its being interlocked-with the latch cage by the detents 142. However, the upward movement" of the latch cage causes the detent bores 14% therein'to register with the upper groove 136 in the latch head 134-, thus permitting the detents 142 to move inwardly into the groove 136; The trigger'cage is biased downwardly by the spring 152, and hence the detents. are cammed out of the groove 14% in the trigger cage and into the groove 136. Subsequent downward='movement of the trigger cage brings the u per cyiindrical'portion' of the wall of the recess 145 into registry with the detents 142, thereby retaining them in-the groove 136.

The above-described upward movement of thespider $3 and the latch sleeve 94 extends the spring -86-and-compresses the spring 118, it being understood that thefioating spider 84, to which the lower end of thespring 86 is secured, is restrained against upward movement by the collapsed packer element. The compressing ofthe' spring- 118 tends to cause the spider 120 to move upwardly, and hence during the cocking operation it is necessary'to temporarily confine the expander arms 122a, 12225, as by gripping the packer element in the region of the expander arms, until the detents 142 have engaged the groove 136 to lock the trigger sleeve 132 and spider 120 against axial movement.

In order to permit inserting of a cocking tool into the housing section 38 a distance sufiicient to enable it to engage the spider $8 in its position as shown in Figure lla, the elements disposed in the housing between the spider 83 and the open upper end of the housing are arranged in a particular manner. Thus each of the spiders 88, 120' and 124 has the same number of webs, with corresponding webs being disposed in axial alignment, as indicated by a comparison of Figures 14, 15 and 16. Each pair of'expander arms 122a, 1221b is also axially aligned with a we of each spider. There are thus formed three uninterrupted segmental passages extending from the open end of the housing to a point beyond the spider 88.

Aspecial cocking tool suitable for this purpose is shown.

in Figures 12 and 13, and comprises an elongated tubular body 208 having an outer diameter somewhat less than the inner diameter of the housing section 33so as to clear the projections 13%, and having an inner diameter. greater than the onterdiameter of the springs 86 and 11S and of the hubs of the spiders $8, 120 and 124. The body 200'is provided with three longitudinal slots 202 extending from one end thereof for a distance somewhat greaterthan the axial spacing between the spiders 124 and 83. The slots are angularly ofiset 120 apart, to correspond to the arrangement of the Webs of the spiders. The entrance end of each slot is flared as at 204 and 206 and merges into a short length of slot 208' slightly wider than the 'widest spider web. The main portion of each slot is of a width approximately twice that of the slot length 208, the juncture of the wide and narrow portions providing a shoulder, 210 which. as shown, is concave. The opposite end'ofjthe. body 209 is provided with, an enlarged head. 212 having a pair of grip rods 214 extending therefrom.

The tool isinserted into the housing through its open: upper end, a web of each spider 124, 120 and SSanda pair of expander arms 122a, 1221) progressively'ent'ering each slot202- as the tool is-inserted'. When the shoulders, 210have'pas'sed'beyond the spider88 the tool is -tumed clockwise, as viewed from above, to cause the shoulders 210 to underlie the respective webs of the spider 88. Thereupon the tool is pulled upwardly to cause the shoulders 210 to engage the webs of the spider 88 and pull the spider up to the position shown in Figure 9a. vDuring this operation the operator grasps the packer element A in the region of the expander arms to prevent their moving outwardly prior to latching of the trigger sleeve 132 and spider 120 in fixed position, as described hereinabove. The automatic latching of the latch sleeve 94 and spider 88 in fixed position, as described above, permits the tool to be lowered slightly, turned counterclockwise and withdrawn. Upon' re-assembly of the housing sections the device is ready to be run in a well.

Although in the foregoing description reference has been made to runningthe assembly into a well and withdrawing it therefrom through the well tubing, it should be understood that it is equally possible and occasionally desirable to runit in the annular space between the tubing and the well casing. This is especially the case if the well is equipped with a pump, the operation of which it is desired to continue While conducting the survey. It is not necessary, in order to effect collapse of the packer element, that the downward pressure for de-energizing the spring 86 be applied to all three of the expander arms by a tubular member concentric with the device; on the contrary, downward pressure applied at a single point on the periphery of the packer element is effective for this purpose.

Hence it is possible to effect collapse of the packer element by drawing it upwardly into the annular space between the tubing and the casing until the lower end of the tubing engages the packer element tangentially at one point.

In the event it is desired to operate the assembly in liquid which is a good electric conductor, such as salt water for example, it may be desirable to initially fill the actuator housing sections 38 and 70 with a non-conducting liquid, of greater specific gravity than the conducting liquid, up to the level of the inlet ports 192 and the slots 80. This will obviate any possibility of shorting out through the liquid the current impulse transmitted to the blasting cap filament. It will be noted that whereas in the lower portion of the intermediate housing section 70 there area number of elements of the electrical circuit which are exposed to the fluid in the housing, this is not the case above the fluid inlet ports 192.

It will be apparent from the foregoing description that we have provided a packer element of unique construction and embodying novel characteristics which have proven in actual practice to be extremely useful and advantageous in connection with the primary intended use of the packer element. 'Also, considering the fact that operating conditions limit the overall diameter of the assembly to a maximum of about 1 /2, and considering the complete cycle of operations performed by the actuator mechanism, it will be apparentthat this mechanism is of relatively simple andfoolproof design and of sturdy, durable construction.

It is to be understood that the single embodiment disclosed herein is merely by way of illustration of the invention and that it is susceptible of various modifications and other embodiments within the spirit of the invention and the scope of the appended claims.

We claim:

l. A well packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges circumferentially overlapping throughout their entire length, and means at each end of the packer element engaging the ends of-said strips and retaining said strips in fixed overlapping relation.

2. A well packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges circumferentially overlapping throughout their entire length, and a ring at each end of the packer element engaging the adjacent ends of said strips.

3. A well packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges circumferentially overlapping, and inner arid outer rings at the ends of said packer element, the end portions of said strips being confined in fixed overlapping relationship between the respective pairs of rings.

4. A well packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis, one edge of each strip circumferentially overlapping one edge of the next adjacent strip, said strips being secured only at their ends, and being adapted to be bowed radially outwardly upon movement of the ends thereof toward each other, and means for engaging and interconnecting adjacent ends of the strips to maintain said overlapping relationship when bowed outwardly.

5. A well packer comprising: a packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis, one edge of each strip circumferentially overlapping one edge of the next adjacent strip, said strips being secured only at their ends; means for engaging and interconnecting adjacent ends of the strips to secure them and maintain said overlapping relation; and means associated with said first mentioned means for eifecting relative movement of the ends of the strips toward each other to bow the intermediate portions of said strips radially outwardly.

6. A well packer comprising: a packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges circumferentially overlapping and secured only at their ends; means for engaging and interconnecting adjacent ends of the strips to secure them. and maintain said overlapping relation; means for applying a radially outwardly directed force to said strips at a point intermediate their ends to effect initial outward buckling of said strips; and means operable upon said initial buckling for effecting relative axial movement of the first mentioned means toward each other to continue said buckling.

7. A well packer comprising: a packer element comprising a fluid tight chamber formed by a coextensive plurality of normally straight, crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges circumferentially overlapping and secured only at their ends; means for engaging and interconnecting adjacent ends of the strips to secure them and maintain said overlapping relation; means for applying axially compressive force between said means tending to effect outward buckling of the strips, the magnitude of said axial force being less than the aggregate columnar strength of the strips; and means for initially buckling said strips outwardly by the application thereto of transverse outward force at a point intermediate the ends thereof whereby the aggregate columnar strength of the strips is reduced below the magnitude of said axial compressive force, thereby rendering said axial compressive force efiective to continue the outward buckling of said strips.

8. A well packer comprising, in combination: a packer element comprising a fluid tight chamber formed by an annular series of coextensive normally straight, longitudinally extending crowned spring metal strips disposed in circumferentially overlapping relation; end members interconnecting the respective ends of said strips; means for applying to said end members an axial compressive force less than the aggregate columnar strength of said series of strips when said strips are straight; and radially expansible means disposed within said packer element and operable to apply radially outwardly directed force to said strips intermediate the ends thereof to initially buckle said strips outwardly and thereby reduce their aggregate columnar strength to less than said axial compresstve force, whereby said axial compressive force is rendered effective to continue the outward buckling of said strips.

9. A well packer comprising, in combination: a packer element comprising a fluid tight chamber formed by an annular series of coextensive normally straight, longitudinally extending crowned spring metal strips disposed long1tud1nally in encircling relationship about a common longitudinal axis with their edges in circumferentially overlapping relation throughout their entire length; end members interconnecting the respective adacent ends of said strips; spring means normally urging one of said end members toward the other end member in a direction biasing said end members towards outward.

bowing of said strips, the force of said spring means being less than the aggregate columnar strength of sand series of strips when said strips are straight; radially expansible means disposed within said packer element and operable when expanded to initially buckle said strips outwardly at a point intermediate their ends, said initial buckling being eliective to reduce the aggregate columnar strength of said strips to less than the force exerted by said spring means, whereby said one end member may be moved by said spring means toward said other end member to bow said strips outwardly against the wall of the well; and an actuator extending within said element and engaging said expansible means for expanding the same.

10. Apparatus as set forth in claim -9, wherein said expansible means comprises at least one pair of arms pivotally connected at their distal ends respectively to one of a pair of members, one of which is axially fixed and the other is axially movable with respect to said other end member, the adjacent ends of said arms being pivotally interconnected on an axis spaced radially outwardly of the axes of pivotal connection of their distal ends to said fixed and movable members, whereby upon movement of said movable member toward said fixed member the pivotally interconnected ends of said arms are moved outwardly to buckle said strips outwardly.

11. A well packer comprising, in combination: a packer element comprising a fluid tight chamber formed by an annular series of coextensive normally straight, longitudinally extending crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges in circumferentially overlapping relation throughout their entire length; end members interconnecting the respective adjacent ends of said said strips; spring means normally urging one of said end members toward the other end member in a direction biasing said end members toward outward bowing of said strips, the force of said spring means being less than the aggregate columnar strength of said series of strips when said strips are straight; radially expansible means within said packer element and operable when expanded to initially buckle said strips outwardly; actuating means extending into said element and engaging said expansible means for expanding said expansible means; and means controllable from the well surface for initiating the operation of said actuating means.

12. A well packer comprising in combination: a packer element comprising a fluid tight chamber for-med by an annular series of coextensive normally straight, longitudinally extending crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges in circumferentially overlapping relation throughout their entire length; end members interconnecting the respective adjacent ends of said strips; spring means normally urging one of said end members toward the other end member in a direction biasing said end members toward outward bowing of said strips, the force of said spring means being less than the aggregate columnar strength of said series of strips when said strips are straight; radially expansible means within said packer element and operable when expanded to initially buckle said strips outwardly, said initial internal buckling being efiective to reduce the aggregate columnar strength of said strips to less than the force exerted by said spring means, whereby said one end member may be moved by said spring means toward said other end member to bow said strips outwardly against the wall of the well; actuating means extending into said elementand engaging said expansible means for expanding said expansible means; a pressure chamber having pressure responsive means therein operatively connected to said actuating means; and means controllable from the surface for developing fluid pressure in said chamber to actuate said pressure responsive means, and thereby initiate operation of said actuating means.

13. Apparatus as set forth in claim 12, wherein said surface-controlled means comprises a body of combustible material in said chamber and electrical means controllable from the surface for igniting said combustible material.

14. A well packer comprising, in combination: a packer element comprising a fluid tight chamber formed by an annular series of coextensive normally straight, longitudinally extending crowned spring metal strips disposed longitudinally in encircling relationship about a common longitudinal axis with their edges in circumferentially overlapping relation throughout their entire length; end members interconnecting the respective adjacent ends of said strips; spring means normally urging one of said end members toward the other end member in a direction biasing said end members toward outward bowing of said strips, the force of said spring means being less than the aggregatecolumnar strength of said series of strips when said strips are straight; radially expansible and retractible means within said packer element operable when expanded to initially buckle said strips outwardly and thereby enable said spring means to bow said strips outwardly against the wall of the well; actuating means extending into said packer and engaging said expansible means for expanding said expansible means; and means operatively interconnecting said actuating means and said spring means and operable, upon enforced retraction of said expansible means, to deenergize s'aid'spring means and thereby permit said strips to resume their normal straight condition.

15. A well packer asset forth in claim 14, wherein said spring means comprises a helical spring, a connecting member interposed between one .end of said spring and said packer element, and a first sleeve member having one end thereof engaged by the other end of said spring; and wherein said actuatingmeans for said expansible means comprises a second sleeve member connected at one end to said expansible means; and whereinvsaid interconnecting means comprises a member operatively interconnecting said first and second sleeve members.

16. A well packer as set forth in claim 14, wherein said spring means comprises a helical spring, a connecting member interposed between one end of said spring and said packer element, and a sleeve member engaged at one end by the other end of said spring, the other end of said sleeve member being .releasably .secured ,to an anchor member axially fixed with respect to said other end member; and wherein said means operatively interconnecting said actuating means and said spring means comprises a release member operable, upon retraction of said expansible means, to release said other end of said sleeve :member. from said-anchor member to thereby de-energize said spring means.

References Cited in the file of thispatent UNITED STATES PATENTS Re. 7,244 Martin July 25, 1876 1,539,242 ,Carder May 26,1925 2,212,619 Roe Aug. 27, 1940 2,248,908 Phillips July 8, 1941 2,392,145 Hall Jan. 1, 1946 

